Police said the chaotic violence began to unfold shortly before 5 p.m. Saturday when Ryan Carnan is believed to have shot his mother to death and set her home on fire in this Los Angeles suburb.
Police Sgt. Craig Dungan said Carnan's brother called authorities to say Carnan had told him he'd killed their mother.
Carnan had never been arrested by the Simi Valley Police Department, but the agency has had "mental health-related" contacts with him, police spokeswoman Stephanie Shannon said Sunday.
About the same time the brother's call came in Saturday, however, police began receiving calls of someone shooting at passers-by in the neighborhood, whose streets are marked with names like Mellow Lane and Nonchalant Drive.
Wendy Thompson told the Ventura County Star she was riding her bike on Mellow Lane when she heard a bang and saw bullets hitting the pavement near her.
"I was like, 'What is that?' at first, then there was a 'bang-bang,' and then I saw them next to me," said Thompson, 44.
She said she looked over to see a man with a gun firing at her.
She wasn't hit.
Shannon said officers caught up with Carnan near a trail called Bridle Path. Still armed, he was riding a tractor in the area on the edge of the city's foothills.
The spokeswoman said that's when police opened fire.
She said the officers have been relieved of duty while that shooting is investigated.